Kellogg D L, Morris S R, Rodriguez S B, Liu Y, Grossmann M, Stagni G, Shepherd A M
Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78284, USA.
J Appl Physiol (1985). 1998 Jul;85(1):175-80. doi: 10.1152/jappl.1998.85.1.175.
During dynamic exercise in the heat, increases in skin blood flow are attenuated in hypertensive subjects when compared with normotensive subjects. We studied responses to passive heat stress (water-perfused suits) in eight hypertensive and eight normotensive subjects. Forearm blood flow was measured by venous-occlusion plethysmography, mean arterial pressure (MAP) was measured by Finapres, and forearm vascular conductance (FVC) was calculated. Bretylium tosylate (BT) iontophoresis was used to block active vasoconstriction in a small area of skin. Skin blood flow was indexed by laser-Doppler flowmetry at BT-treated and untreated sites, and cutaneous vascular conductance was calculated. In normothermia, FVC was lower in hypertensive than in normotensive subjects (P < 0.01). During heat stress, FVC rose to similar levels in both groups (P > 0.80); concurrent cutaneous vascular conductance increases were unaffected by BT treatment (P > 0.60). MAP was greater in hypertensive than in normotensive subjects during normothermia (P < 0.05, hypertensive vs. normotensive subjects). During hyperthermia, MAP fell in hypertensive subjects but showed no statistically significant change in normotensive subjects (P < 0.05, hypertensive vs. normotensive subjects). The internal temperature at which vasodilation began did not differ between groups (P > 0.80). FVC is reduced during normothermia in unmedicated hypertensive subjects; however, they respond to passive heat stress in a fashion no different from normotensive subjects.
在高温环境下进行动态运动时，与血压正常的受试者相比，高血压受试者的皮肤血流量增加会减弱。我们研究了8名高血压受试者和8名血压正常受试者对被动热应激（水灌注服）的反应。通过静脉阻断体积描记法测量前臂血流量，通过Finapres测量平均动脉压（MAP），并计算前臂血管传导率（FVC）。使用溴苄铵（BT）离子电渗疗法阻断皮肤小区域的主动血管收缩。通过激光多普勒血流仪在BT处理部位和未处理部位对皮肤血流量进行指数化，并计算皮肤血管传导率。在正常体温下，高血压受试者的FVC低于血压正常的受试者（P < 0.01）。在热应激期间，两组的FVC均上升至相似水平（P > 0.80）；同时皮肤血管传导率的增加不受BT治疗的影响（P > 0.60）。在正常体温下，高血压受试者的MAP高于血压正常的受试者（P < 0.05，高血压受试者与血压正常的受试者相比）。在体温过高期间，高血压受试者的MAP下降，但血压正常的受试者未显示出统计学上的显著变化（P < 0.05，高血压受试者与血压正常的受试者相比）。血管舒张开始时的内部温度在两组之间没有差异（P > 0.80）。未接受药物治疗的高血压受试者在正常体温下FVC降低；然而，他们对被动热应激的反应方式与血压正常的受试者没有不同。
